by William Lulow
Making an image using long exposure times is a technique as old as photography itself. In the mid-1840s, Joseph Niepce was experimenting with making exposures in France because there certainly weren’t fast emulsions around then. He was trying to fix an image on a light-sensitive emulsion. He made an exposure that probably lasted around 20 minutes or so of the Champs Elysee in Paris. When he looked at the image, there were no people, horses or anything else except the buildings. There was, however, an image of a man who was standing stock still getting his shoes shined on a corner. It was a bit blurry, but he was there. The reason he showed up on the emulsion was precisely because he was not moving – at least not very much. What happens is that with exceedingly long exposure times, the emulsion or a CCD, for that matter, doesn’t show a moving subject. It’s moving too fast to be recorded. It’s a great technique that I have used often when photographing public places. A photographer named Marie Cosindas actually had to photograph the painting “Mona Lisa” at the Louvre Museum in Paris. She noticed that the room where it was hanging was always full of people who had come to see the famous painting. So, she stopped her lens way down to f/32, then added some filters which cut down on the light, thus increasing the exposure time, and made about a 10 minute exposure. She got an image of the painting without any people in the room because they were all moving.
Here is an image of some steps in Central Park. You can notice a faint blur in the middle which was caused by some people who had paused for a second or two on the steps. The exposure was f/22 at about 20 seconds.